Device for setting target vehicle, system for setting target vehicle, and method for setting target vehicle

ABSTRACT

A device for setting a target vehicle that sets a target vehicle to be subjected to driving assistance control of a host vehicle includes: a detection signal acquisition device capable of acquiring a first detection signal representing an object by an image, and a second detection signal representing the object by a reflection point; and setting control unit, which determines whether to set a forward object as a target vehicle, wherein if a movement history is not associated with the forward object, and a combination history is associated with the forward object, then as a selection threshold of a first determination parameter for determining whether to set the forward object as the target vehicle, a selection threshold is used such that the forward object is less likely to be selected as the target vehicle than with the selection threshold which would be used if a movement history is associated with the forward object.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 16/829,984, filed on Mar. 25, 2020, which is abypass application of International Application No. PCT/JP2018/028242,filed on Jul. 27, 2018, which designated the U.S. and claims priority toJapanese Patent Application No. 2017-187659, filed on Sep. 28, 2017, thecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a technique for setting a targetvehicle to be subjected to driving assistance control of a host vehicle.

BACKGROUND

A driving assistance control technique is known that supports driving ofa host vehicle with respect to a forward object using a detection signalfrom an object detector, such as a camera or radar. A driving assistancecontrol technique is sought which is capable of appropriately setting,from among forward object, a target vehicle to be subjected to drivingassistance control of the host vehicle. For example, proposed is atechnique for appropriately setting, from among forward object, aforward object that exists in the same lane as the host vehicle as atarget vehicle, that is, as a preceding vehicle (for example, see JPH8-279088 A).

SUMMARY

A first aspect provides a device for setting a target vehicle that setsa target vehicle to be subjected to driving assistance control of a hostvehicle. The device for setting a target vehicle according to the firstaspect includes: a detection signal acquisition device capable ofacquiring a first detection signal representing an object by an image,and a second detection signal representing the object by a reflectionpoint; and a setting control unit which determines whether to set aforward object as a target vehicle, wherein if a movement history, whichindicates that the forward object has been detected as a mobile object,is not associated with the forward object, and a combination history,which indicates that the forward object has been determined to be avehicle using a combination of the first detection signal and the seconddetection signal, is associated with the forward object, then as aselection threshold of a first determination parameter for determiningwhether to set the forward object as the target vehicle, a selectionthreshold is used such that the forward object is less likely to beselected as the target vehicle than with the selection threshold whichwould be used if a movement history is associated with the forwardobject.

A second aspect provides a method for setting a target vehicle that setsa target vehicle to be subjected to driving assistance control of a hostvehicle. The method for setting a target vehicle according to the secondaspect includes: acquiring a first detection signal representing anobject by an image, and a second detection signal representing theobject by a reflection point; and determining whether to set a forwardobject as a target vehicle, wherein if a movement history, whichindicates that the forward object has been detected as a mobile object,is not associated with the forward object, and a combination history,which indicates that the forward object has been determined to be avehicle using a combination of the first detection signal and the seconddetection signal, is associated with the forward object, then as aselection threshold of a first determination parameter for determiningwhether to set the forward object as the target vehicle, a selectionthreshold is used such that the forward object is less likely to beselected as the target vehicle than with the selection threshold whichwould be used if a movement history is associated with the forwardobject.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and other objects, features and advantages of thepresent disclosure will be made clearer by the following detaileddescription, given referring to the appended drawings. In theaccompanying drawings:

FIG. 1 is an explanatory diagram showing a vehicle equipped with adevice for setting a target vehicle according to a first embodiment;

FIG. 2 is a block diagram showing a functional configuration of acontrol device included in the device for setting a target vehicleaccording to the first embodiment;

FIG. 3 is a flowchart showing a process flow of target vehicle settingprocessing and driving assistance control processing; which are executedby the device for setting a target vehicle according to the firstembodiment;

FIG. 4 is a flowchart showing a process flow of the target vehiclesetting processing as the first embodiment;

FIG. 5 is an explanatory diagram showing the relationship between a hostvehicle and a forward object; and describes a relative lateral distancethat serves as a first determination parameter;

FIG. 6 is an explanatory diagram showing the relationship between a hostvehicle and a forward object when a moving vehicle threshold is set asthe selection threshold of the first determination parameter;

FIG. 7 is an explanatory diagram showing the relationship between a hostvehicle and a forward object when a stationary vehicle threshold is setas the selection threshold of the first determination parameter;

FIG. 8 is a flowchart showing a process flow of the target vehiclesetting processing as a second embodiment;

FIG. 9 is an explanatory diagram showing the relationship between a hostvehicle and a forward object; and describes an overlap parameter thatserves as an additional parameter;

FIG. 10 is an explanatory diagram showing the relationship between ahost vehicle and a forward object; and describes a protrusion parameterthat serves as an additional parameter;

FIG. 11 is an explanatory diagram showing the relationship between ahost vehicle and a forward object in a case where the setting of thetarget vehicle is inhibited;

FIG. 12 is an explanatory diagram showing the relationship between ahost vehicle and a forward object in a case where the setting of thetarget vehicle is not inhibited;

FIG. 13 is an explanatory diagram showing the relationship between ahost vehicle and a forward object in a case where the setting of thetarget vehicle is not inhibited;

FIG. 14 is an explanatory diagram showing the relationship between ahost vehicle and a forward object in a case where the setting of thetarget vehicle is inhibited while driving assistance control processingis being executed;

FIG. 15 is an explanatory diagram showing the relationship between ahost vehicle and a forward object in a case where the setting of thetarget vehicle is not inhibited while driving assistance controlprocessing is being executed; and

FIG. 16 is a flowchart showing a process flow of driving assistancecontrol processing as a third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

If the forward object does not exist on the same travel trajectory asthe host vehicle, and the target vehicle is uniformly set withoutconsideration of stationary vehicles with a low likelihood of moving,and moving vehicles which have a movement history or which are currentlymoving, the execution frequency of driving assistance control increases,which hinders the smooth driving of the host vehicle, and further, maygive the driver the impression that the driving assistance control isexcessive.

Therefore, it is desired to appropriately set the target vehicleaccording to whether a forward object is a stationary vehicle or amoving vehicle.

The present disclosure has been made in order to solve the problemsdescribed above, and is achievable as the following aspects.

A first aspect provides a device for setting a target vehicle that setsa target vehicle to be subjected to driving assistance control of a hostvehicle. The device for setting a target vehicle according to the firstaspect includes: a detection signal acquisition device capable ofacquiring a first detection signal representing an object by an image,and a second detection signal representing the object by a reflectionpoint; and a setting control unit which determines whether to set aforward object as a target vehicle, wherein if a movement history, whichindicates that the forward object has been detected as a mobile object,is not associated with the forward object, and a combination history,which indicates that the forward object has been determined to be avehicle using a combination of the first detection signal and the seconddetection signal, is associated with the forward object, then as aselection threshold of a first determination parameter for determiningwhether to set the forward object as the target vehicle, a selectionthreshold is used such that the forward object is less likely to beselected as the target vehicle than with the selection threshold whichwould be used if a movement history is associated with the forwardobject.

According to the device for setting a target vehicle of the firstaspect, setting of the target vehicle can be appropriately executedaccording to whether a forward object is a stationary vehicle or amoving vehicle.

A second aspect provides a method for setting a target vehicle that setsa target vehicle to be subjected to driving assistance control of a hostvehicle. The method for setting a target vehicle according to the secondaspect includes: acquiring a first detection signal representing anobject by an image, and a second detection signal representing theobject by a reflection point; and determining whether to set a forwardobject as a target vehicle, wherein if a movement history, whichindicates that the forward object has been detected as a mobile object,is not associated with the forward object, and a combination history,which indicates that the forward object has been determined to be avehicle using a combination of the first detection signal and the seconddetection signal, is associated with the forward object, then as aselection threshold of a first determination parameter for determiningwhether to set the forward object as the target vehicle, a selectionthreshold is used such that the forward object is less likely to beselected as the target vehicle than with the selection threshold whichwould be used if a movement history is associated with the forwardobject.

According to the method for setting a target vehicle of the secondaspect, the target vehicle can be appropriately set according to whethera forward object is a stationary vehicle or a moving vehicle. Thepresent disclosure may also be realized as a program for setting atarget vehicle, or a computer-readable recording medium that has theprogram recorded thereon.

Hereinafter, a device for setting a target vehicle, a system for settinga target vehicle, and a method for setting a target vehicle according tothe present disclosure will be described based on several embodiments.

First Embodiment

As shown in FIG. 1, a device for setting a target vehicle 10 accordingto a first embodiment is used by being installed on a vehicle 500. Thedevice for setting a target vehicle 10 includes at least a controldevice 100, and a system for setting a target vehicle includes, inaddition to the device for setting a target vehicle 10, a radar ECU 21,a camera ECU 22, a yaw rate sensor 23, a wheel speed sensor 24, arotation angle sensor 25, a throttle drive device 31, and a brakeassistance device 32. The vehicle 500 includes an internal combustionengine ICE, wheels 501, braking devices 502, brake lines 503, a steeringwheel 504, a windscreen 510, and a front bumper 520. The radar ECU 21 isconnected to a millimeter-wave radar 211, which emits a radio wave anddetects a reflected wave from an object, and uses the reflected waveacquired by the millimeter-wave radar 211 to generate and output adetection signal that represents the object by a reflection point. Thecamera ECU 22 is connected to the forward camera 221 and generates andoutputs a detection signal indicating an object by an image using theimage acquired by the forward camera 221 and a shape pattern of theobject prepared in advance. Each ECU is a microprocessor including acalculation unit, a storage unit, and an I/O unit. The radar ECU 21 andthe millimeter-wave radar 211 correspond to a first detection unit, andthe camera ECU 22 and the forward camera 221 correspond to a seconddetection unit. The detector for detecting the reflected wave may use,in addition to the millimeter-wave radar 211, a LIDAR (laser radar) oran ultrasonic detector that emits a sound wave and detects a reflectedwave. The imaging unit that captures the object may use, in addition tothe forward camera 221, a stereo camera or a multi-camera configured bytwo or more cameras.

In the vehicle 500, the internal combustion engine ICE is provided witha throttle drive device 31 that drives a slot valve for controlling theoutput of the internal combustion engine ICE by adjusting an intake airamount. When a diesel engine having a constant intake air amount isprovided as the internal combustion engine ICE, a fuel injection devicedrive device that controls the fuel injection amount from the fuelinjection device can be used instead of the throttle valve drive device31. In the vehicle 500, a braking device 502 is provided on each wheel501. The braking devices 502 realize the braking of the wheels 501 bymeans of a brake fluid pressure supplied via the brake lines 503 inresponse to a brake pedal operation performed by the driver. The brakelines 503 include a brake piston and a brake fluid line for producingthe brake fluid pressure in response to a brake pedal operation. In thepresent embodiment, the brake assistance device 32 is provided on thebrake lines 503, and is capable of controlling the fluid pressureindependently of the brake pedal operation, thereby realizing brakingassistance. The brake lines 503 may represent control signal linesinstead of brake fluid lines, and a configuration which causes anactuator provided in each braking device 502 to be operated may beemployed. The steering wheel 504 is connected to the front wheels 501via a steering mechanism 505 which includes a steering rod. As a drivingassistance control, the throttle drive device 31 and the brakeassistance device 32 realize constant travel speed/inter-vehicledistance control processing, which causes the host vehicle to be drivenat a set vehicle speed while maintaining a constant inter-vehicledistance between the preceding vehicle and the host vehicle, that is, anadaptive cruise control (ACC). In addition to this, the drivingassistance includes steering assistance (not shown) that performssteering control of the steering mechanism, which includes the steeringwheel and the steering rod, independently of the operation of thesteering wheel by the driver, and these operations can be controlled bya driving assistance device which includes the functions of the brakeassistance device.

As shown in FIG. 2, the control device 100 includes a central processingunit (CPU) 101, a memory 102, an I/O interface 103, and a bus 104. TheCPU 101, the memory 102, and the I/O interface 103 are connected via thebus such that bidirectional communication is possible. The memory 102includes a non-volatile and read-only memory, such as a ROM, that storesa program for setting a target vehicle P1 to be subjected to drivingassistance control of a host vehicle and a program for drivingassistance P2 for executing driving assistance control, and a memorywhich is readable/writable by the CPU 101, such as a RAM. As describedbelow, the memory 102 can further store a flag indicating that amovement history exists and a flag indicating that an FSN historyexists. The CPU 101 functions as a setting control unit by expanding andexecuting the program for setting a target vehicle P1 stored in thememory 102 in the readable/writable memory, and functions as a drivingassistance control unit by similarly executing the program for drivingassistance P2. The CPU 101 may be a single CPU, a plurality of CPUs thatexecute each program, or a multithreading CPU capable of simultaneouslyexecuting a plurality of programs.

The radar ECU 21, the camera ECU 22, the yaw rate sensor 23, the wheelspeed sensor 24, the rotation angle sensor 25, the throttle drive device31, and the brake assistance device 32 are each connected to the I/Ointerface 103 via control signal lines. Detection signals are input fromthe radar ECU 21, the camera ECU 22, the yaw rate sensor 23, the wheelspeed sensor 24, the rotation angle sensor 25, a control signal thatcontrols the opening level of the throttle valve is output to thethrottle drive device 31, and a control signal that controls the brakinglevel is output to the brake assistance device 32. The I/O interface 103can be referred to as a detection signal acquisition unit capable ofacquiring a first detection signal and a second detection signal.

The millimeter-wave radar 211 is a sensor that detects the distance,relative speed, and angle of an object by emitting a millimeter wave andreceiving a reflected wave reflected by the object. In the presentembodiment, the millimeter-wave radar 211 is disposed on the center andon both sides of the front bumper 520. An unprocessed detection signaloutput from the millimeter-wave radar 211 is processed by the radar ECU21, and input to the control device 100 as a first detection signalcomposed of a point or a sequence of points representing one or morerepresentative positions on the object. Alternatively, in the absence ofthe radar ECU 21, a signal representing an unprocessed received wave maybe supplied from the millimeter-wave radar 211 to the control device 100as the first detection signal. When an unprocessed received wave is usedas the detection signal, the control device 100 executes signalprocessing for specifying the position and distance of the object.

The forward camera 221 is an imaging device provided with a singleimaging element such as a CCD, and is a sensor that, as a result ofreceiving visible light, outputs external shape information relating toan object as image data, which is the detection result. The image dataoutput from the forward camera 221 is subjected to feature pointextraction processing in the camera ECU 22, and patterns representingthe extracted feature points are compared with that of an objectprepared in advance to be set as a control subject, that is, with acomparison patterns representing the external shape of a vehicle, and aframe image which includes the identified object is generated if theextracted patterns and the comparison patterns coincide, or are similar.On the other hand, if the extracted patterns and the comparison patternsdo not coincide or are not similar, that is, are dissimilar, no frameimage is generated. If a plurality of object is included in the imagedata, the camera ECU 22 generates a plurality of frame images includingeach of the identified object, which are then input to the controldevice 100 as second detection signals. Each frame image is representedby pixel data, and includes position information, that is, coordinateinformation, of the identified object. The number of frame images thatcan be included in a detection signal depends on the bandwidth betweenthe camera ECU 22 and the control device 100. The unprocessed image datacaptured by the forward camera 221 may be input to the control device100 as a second detection signal without separately providing the cameraECU 22. In this case, the control device 100 may identify the objectusing the external shape pattern of the object. In the presentembodiment, the forward camera 221 is disposed on an upper portion ofthe center of the windscreen 510. The pixel data output from the forwardcamera 221 is monochrome pixel data or color pixel data. When it isdesirable for an object other than a vehicle to be set as a controlsubject, an external pattern of the desired object is prepared, and thecamera ECU 22 may output a frame image including the desired object as adetection signal. In this case, a frame image suitable for processingmay be selectively used in the subsequent processing in the controldevice 100.

The yaw rate sensor 23 is a sensor that detects the rotational angularvelocity of the vehicle 500. The yaw rate sensor 23 is disposed, forexample, in a central portion of the vehicle. The detection signaloutput from the yaw rate sensor 23 is a voltage value which isproportional to the rotation direction and the angular velocity.

The wheel speed sensor 24 is a sensor that detects the rotational speedof the wheel 501, and is provided on each wheel 501. The detectionsignal output from the wheel speed sensor 24 is a voltage valueproportional to the wheel speed or a pulse wave having an intervalcorresponding to the wheel speed. Information such as the vehicle speedand the travel distance of the vehicle can be acquired using thedetection signal from the wheel speed sensor 24.

The rotation angle sensor 25 is a torque sensor that detects a torsionamount generated in the steering rod by steering of the steering wheel504, that is, a steering torque. In the present embodiment, the rotationangle sensor 25 is provided on the steering rod that connects thesteering wheel 504 and the steering mechanism. The detection signaloutput from the rotation angle sensor 25 is a voltage value proportionalto the torsion amount.

The throttle drive device 31 is an actuator such as a stepping motor foradjusting the opening level of the throttle valve and controlling theoutput of the internal combustion engine ICE in response to anaccelerator pedal operation by the driver, or irrespective of anaccelerator pedal operation by the driver. A driver that controls theoperation of the actuator based on a control signal from the CPU 101 ismounted on the throttle drive device 31. In the present embodiment, thethrottle drive device 31 is provided in an air intake manifold, andincreases or decreases the amount of air taken in by the internalcombustion engine ICE according to a control signal from the controldevice 100.

The brake assistance device 32 is an actuator for realizing braking bythe braking device 502 irrespective of a brake pedal operation by thedriver. A driver that controls the operation of the actuator based on acontrol signal from the CPU 101 is mounted on the brake assistancedevice 32. In the present embodiment, the brake assistance device 32 isprovided on the brake lines 503, and the hydraulic pressure in the brakelines 503 is increased or decreased according to a control signal fromthe control device 100. The brake assistance device 32 is constituted bya module including, for example, an electric motor and a hydraulicpiston driven by the electric motor. Alternatively, a brake controlactuator already introduced as a side slip prevention device or antilockbraking system may also be used.

The target vehicle setting processing and the driving assistance controlprocessing, which are executed by the device for setting a targetvehicle 10 according to the first embodiment, will be described. Theprocessing routine shown in FIG. 3 is repeatedly executed atpredetermined time intervals, for example, from the start to the stop ofthe control system of the vehicle, or when a start switch is switched onuntil the start switch is switched off. The target vehicle settingprocessing S10 is executed when the CPU 101 executes the program forsetting a target vehicle P1, and the driving assistance controlprocessing S20 is executed when the driving assistance control programP2 is executed. In FIG. 3, the target vehicle setting processing S10 andthe driving assistance control processing S20 are included in the sameprocessing flow in order to simplify the description, but the targetvehicle setting processing S10 and the driving assistance controlprocessing S20 are processes that may be independently executed withseparate timings. The driving assistance control processing S20includes, for example, constant travel speed/inter-vehicle distancecontrol processing, braking support processing, and steering supportprocessing. The braking support processing includes sudden braking andgentle braking for avoiding a collision with the target vehicle, and thesteering assistance processing includes steering for avoiding acollision with the target vehicle and steering for preventing lanedeparture.

The target vehicle setting processing S10 as the first embodiment willbe described in detail with reference to FIG. 4 to FIG. 6. The flowchartshown in FIG. 4 is repeatedly executed at predetermined time intervals.The CPU 101 acquires attribute information about a forward object viathe radar ECU 21 and the camera ECU 22 (step S100). Because the forwardobject is subjected to a determination, it can also be referred to as adetermination object. The CPU 101 determines whether the object detectedby the millimeter-wave radar 211 has moved each time a piece ofinformation about the forward object is acquired, and associates withthe detected object a movement history that indicates the existence ofmovement. Specifically, after the present processing routine is startedfor the first time, the CPU 101 determines, with respect to an objectdetected for the first time by the millimeter-wave radar 211, thepresence of movement of the object based on a change in the relativespeed and in the position coordinates of the reflection pointscorresponding to the target at each acquisition timing. For example, ifthe CPU 101 determines that the subject is moving, it associates a flagindicating that a movement history exists, which is indicative of amobile object, and when the CPU 101 identifies that the object is notmoving, it associates a flag indicating that no movement history exists,which is indicative of a stationary object. Further, the CPU 101 usesthe detection signal input from the radar ECU 21 and the detectionsignal input from the camera ECU 22 to perform data fusion processing,that is, data integration processing or join processing, which improvesthe system for determining whether the object is a vehicle.Specifically, the CPU 101 performs integration if the positioncoordinates of the reflection points representing the object input fromthe radar ECU 21, and the detection signal input from the camera ECU 22,that is, the position coordinates of the identified vehicle included inthe image frame, are to be associated, and associates with the object aflag indicating that a fusion (FSN) history exists, that is, that acombination history exists, which indicates that the object has beenidentified as a vehicle. On the other hand, if a vehicle correspondingto the position coordinates of the reflection points representing theobject does not appear in the image frame and the association cannot beperformed, a flag indicating that no fusion history exists is associatedwith the object. An object which is associated with a flag indicatingthat an FSN history exists represents a stationary vehicle which hasbeen identified as a vehicle through vehicle identification by patternmatching, and an object which is associated with a flag indicating thatno FSN history exists represents an unknown stationary object whoseobject type has not been specified. If a plurality of forward objectcould exist, then the detection signals input from the radar ECU 21 andthe camera ECU 22 may include a plurality of object, and therefore, datafusion processing is executed with respect to each object. The detectionof an object using the millimeter-wave radar 211 is not easily affectedby forward obstacles, weather, or the like, and therefore, the objectmay sometimes not be detected by the forward camera 221 despite theobject being detected by the millimeter-wave radar 211, and data fusionprocessing cannot be executed in such cases. The movement history flagand the FSN history flag are initialized every time the system of thevehicle 500 is activated, that is, reset to the no movement history andno FSN history states.

The CPU 101 determines whether a flag indicating that a movement historyexists is associated with the forward object whose information wasacquired in step S100, or whether the forward object is a mobile objectwhich is currently moving (step S110). In the present embodiment, inorder to avoid redundancy of description, when the forward object isreferred to as being associated with a flag indicating that a movementhistory exists, this collectively includes those cases the forwardobject is a mobile object. If the forward object is associated with aflag indicating that a movement history exists (step S110: Yes), the CPU101 sets a moving vehicle threshold Dr1 as the selection threshold Dr ofthe first determination parameter used in step S130 to assess whether toperform the setting as the target vehicle (step S120). That is, even ifthe forward object is a stationary object, a moving vehicle threshold isset as a selection threshold if it is associated with a flag indicatingthat a movement history exists. When the CPU 101 sets the selectionthreshold, the process proceeds to step S130. As shown in FIG. 5, thefirst determination parameter used in step S130 is a relative lateraldistance D1 of the forward vehicle M2 with respect to the host vehicleM0, and the selection threshold Dr is the threshold of the relativelateral distance D1.

The CPU 101 calculates the relative lateral distance D1 of the forwardvehicle M2 with respect to the host vehicle M0, and uses the movingvehicle threshold Dr1 which has been set to determine whether D1 is lessthan Dr1, that is, whether the first determination parameter is lessthan the selection threshold (step S130). For example, the relativelateral distance D1 between the forward vehicle M2 and the host vehicleM0 can be calculated using the position coordinates of a reflectionpoint on an end portion of the forward vehicle M2 on the host vehicle M0side input from the radar ECU 21 and an end point of the host vehicle onthe forward vehicle M2 side, and then taking the difference as theseparation amount. Alternatively, it may be calculated using thepositional coordinates of an end point of the forward vehicle M2 on thehost vehicle M0 side obtained from an image frame input from the cameraECU 22 that includes the forward vehicle M2, and then taking thedifference as the separation amount.

If the CPU 101 determines that D1 is less than Dr1 (step S130: Yes), itsets the forward vehicle M2 as the target vehicle (step S140), and thepresent processing routine ends. If the CPU 101 determines that D1 isnot less than Dr1 (step S130: No), it does not set the forward vehicleM2 as the target vehicle (step S170), and the present processing routineends.

If a flag indicating that a movement history exists is not associatedwith the forward object (step S110: No), the CPU 101 determines whethera flag indicating that an FSN history exists is associated with theforward object (step S150). It is determined whether the forward objecthas been subjected to data fusion processing even once since the startof detection by the millimeter-wave radar 211 and the forward camera221, that is, has been determined as a stationary vehicle as a result ofdata fusion processing. If a flag indicating that an FSN history existsis not associated with the forward object (step S150: No), the CPU 101does not set the forward vehicle M2 as a target vehicle (step S170), andthe present processing routine ends.

If the forward object is associated with a flag indicating that an FSNhistory exists (step S150: Yes), the CPU 101 sets the selectionthreshold Dr of the first determination parameter used when setting thetarget vehicle as a stationary vehicle threshold Dr2 (step S160). Astationary vehicle threshold Dr2 is set to a value that makes it lesslikely for a stationary vehicle to be selected as the target vehiclethan a moving vehicle. In the present embodiment, because a distancedifference between the forward vehicle M2 and the host vehicle M0 isused as the first determination parameter, the stationary vehiclethreshold Dr2 is set to a smaller value than the moving vehiclethreshold Dr1, and the moving vehicle threshold Dr1 is greater than thestationary vehicle threshold Dr2. That is, if the forward vehicle M2 isa stationary vehicle, it is only determined to be the target vehiclewhen the distance difference between the forward vehicle M2 and the hostvehicle M0 becomes small, which makes it less likely to be selected asthe target vehicle than a moving vehicle. A value is used for thestationary vehicle threshold Dr2 that makes it less likely for astationary vehicle to be selected as the target vehicle than a movingvehicle because, compared to a moving vehicle or a case where a movementhistory exists, the likelihood of a stationary vehicle unexpectedlystarting to move is low, and therefore, setting as the target vehicleand implementing driving assistance control would lead to excessiveimplementation of the driving assistance control. If an overlap amountthat represents the extent of overlap between the forward vehicle M2 andthe host vehicle M0 is used as the first determination parameter, thestationary vehicle threshold Dr2 is set to a larger value than themoving vehicle threshold Dr1. In this case, if the forward vehicle M2 isa stationary vehicle, it is only determined to be the target vehiclewhen the overlap amount between the forward vehicle M2 and the hostvehicle M0 becomes large, which makes it less likely to be selected asthe target vehicle than a moving vehicle. This is because, even if theoverlap amount is large between the forward vehicle M2, which is astationary vehicle, and the host vehicle M0, the likelihood of acollision or contact between the host vehicle M0 and the forward vehicleM2 is low relative to the case of a moving vehicle.

The CPU 101 calculates the relative lateral distance D1 of the forwardvehicle M2 with respect to the host vehicle M0, and uses the stationaryvehicle threshold Dr2 that has been set to determine whether D1 is lessthan Dr2, that is, whether the first determination parameter is lessthan the selection threshold (step S130). If the CPU 101 determines thatD1 is less than Dr2 (step S130: Yes), it sets the forward vehicle M2 asthe target vehicle (step S140), and the present processing routine ends.If the CPU 101 determines that D1 is not less than Dr2 (step S130: No),it does not set the forward vehicle M2 as a target vehicle (step S170),and the present processing routine ends.

According to the device for setting a target vehicle 10 of the firstembodiment, different selection thresholds are used to determine whetherto set the target vehicle when the forward object is associated with aflag indicating that a movement history exists, and when the forwardobject is not associated with a movement history but is associated witha flag indicating that an FSN continuation history exists. Therefore,the target vehicle can be appropriately set according to whether theforward object is a stationary vehicle or a moving vehicle, and further,driving assistance control can be appropriately executed.

This will be specifically described using FIG. 6 and FIG. 7. Forexample, the example shown in FIG. 6 corresponds to a case where, forexample, the forward vehicles M1 and M2 were both initially traveling ina lane, and the forward vehicle M2 has then stopped on the shoulder ofthe road. In this case, the forward vehicle M2 is associated with a flagindicating that a movement history exists. For example, in the exampleshown in FIG. 7, the forward vehicle M2 is stopped on the shoulder ofthe road from the start of detection by the millimeter-wave radar 211and the forward camera 221, and is further associated with a flagindicating that an FSN history exists. In this case, the forward vehicleM2 is recognized as a stationary vehicle. The forward vehicles M1 and M2shown in FIG. 6 are set as vehicles necessitating control, and drivingassistance control is executed with respect to the forward vehicles M1and M2 according to the distance from the host vehicle M0, the relativespeed, or the like. In FIG. 7, because the forward vehicle M1, whichexists on the travel trajectory of the host vehicle M0, is in astationary state after moving and has a movement history, it is set asthe target vehicle, while the forward vehicle M2 is not set as thetarget vehicle because is a stationary vehicle having an FSN history.Therefore, driving assistance control is not executed when the hostvehicle M0 approaches and passes the forward vehicle M2, and excessiveexecution of driving assistance control is inhibited. As a result,smooth vehicle travel can be realized, and control assistance unintendedby the driver, that is, deceleration and steering assistance, are notexecuted, and the driver does not experience discomfort. When the term“travel trajectory” is used in relation to the forward vehicle M2, thetravel trajectory refers to the planned travel trajectory of the hostvehicle M0.

In the first embodiment, the processing that sets the target vehicle instep S140 more specifically includes a step that determines a pluralityof candidates for the target vehicle, and a step that sets, from amongthe plurality of candidates for the target vehicle, one candidate forthe target vehicle as the target vehicle. That is, if a plurality offorward object exist and a plurality of forward object have a movementhistory or an FSN history, a plurality of candidates for the targetvehicle can be determined. For example, the setting of a single targetvehicle is executed on the condition that it has the shortest distanceto the host vehicle among the plurality of candidates for the targetvehicle, and has the highest relative speed with respect to the hostvehicle, and then the forward object that has been set, which is acandidate for the target vehicle, is associated with a flag indicatingthat it is the target vehicle. This processing content can be similarlyapplied to each of the following embodiments.

Second Embodiment

A target vehicle setting processing as a second embodiment, which isexecuted by the device for setting a target vehicle 10, will bedescribed with reference to FIG. 8 to FIG. 15. The configurations of thevehicle 500, the device for setting a target vehicle 10, and the systemfor setting a target vehicle are the same as the configurations of thefirst embodiment, and therefore, the same reference numerals are givenand the description is omitted. Furthermore, the same processing stepsas those of the target vehicle setting processing as the firstembodiment are given the same step numbers, and the description isomitted. The flowchart shown in FIG. 8 is repeatedly executed atpredetermined time intervals in the same manner.

The CPU 101 executes step S100 and step S110. If it is determined thatthe forward object is associated with a movement history flag (stepS110: Yes), the CPU 101 sets the moving vehicle threshold Dr1 as theselection threshold of the first determination parameter in step S120,and the process proceeds to step S130. If the CPU 101 determines that D1is less than Dr1 (step S130: Yes), it sets the forward vehicle M2 as thetarget vehicle (step S140), and the present processing routine ends. Ifthe CPU 101 determines that D1 is not less than Dr1 (step S130: No), itsets the forward vehicle M2 as the target vehicle (step S170), and thepresent processing routine ends.

If a flag indicating that a movement history exists is not associatedwith the forward object (step S110: No), the CPU 101 determines whethera flag indicating that an FSN history exists is associated with theforward object (step S150), and if a flag indicating that a FSN historyexists is not associated with the forward object (step S150: No), theforward vehicle M2 is not set as the target vehicle (step S170), and thepresent processing routine ends.

If the forward object is associated with a flag indicating that an FSNhistory exists (step S150: Yes), the CPU 101 sets the stationary vehiclethreshold Dr2 as the selection threshold Dr of the first determinationparameter used when setting the target vehicle, and sets at least onestationary vehicle parameter (step S162). The stationary vehicleparameter is an additional parameter which is different from the firstparameter which is used to determine whether to set a stationary vehicleas the target vehicle.

At least one of the following parameters may be used as the additionalparameter.

(1) An overlap parameter as shown in FIG. 9, which represents an overlapamount D2 between a forward vehicle M2, which straddles a shoulder laneSL and is stationary on the shoulder of the road, and a host vehicle M0.The selection threshold of the overlap amount D2 uses, for example, avalue of zero or more, that is, at least a value in which the hostvehicle M0 would make contact or collide with the forward vehicle M2,which is a stationary vehicle, if it proceeds as is. That is, if thereis no possibility of a collision between the forward vehicle M2, whichis a stationary vehicle, and the host vehicle M0, the forward vehicle M2is not set as the target vehicle. The overlap amount D2 between astationary vehicle and the host vehicle M0 is acquired, for example,using the position coordinates of a reflection point on an end portionof the forward vehicle M2 on the host vehicle M0 side input from theradar ECU 21 and an end point of the host vehicle on the forward vehicleM2 side, and then calculating the difference as the overlap amount.Alternatively, it may be acquired using the positional coordinates of anend point of the forward vehicle M2 on the host vehicle M0 side obtainedfrom an image frame input from the camera ECU 22 that includes theforward vehicle M2, and then calculating the difference as the overlapamount. In this case, as described above, the stationary vehiclethreshold Dr2 is set to a larger value than the moving vehicle thresholdDr1. Alternatively, it may be calculated as a white line overlap amount,which indicates how much the forward vehicle M2 is protruding from theshoulder line SL, or as a white line lap parameter, which represents awhite line lap ratio. Specifically, a difference distance between theposition coordinates of the center of the shoulder line SL and an endpoint of the forward vehicle M2 on the host vehicle M0 side iscalculated as the white line overlap amount. The white line lap ratio iscalculated, for example, as a ratio of the white line overlap amount tothe vehicle width of the forward vehicle M2. The selection threshold ofthe white line overlap amount or white line lap ratio may use a valuewith respect to the lane width that could cause a collision between theforward vehicle M2, which is a stationary vehicle, and the host vehicleM0, such as a value of 1 m or more for the selection threshold of thewhite line overlap amount, or a value of 50% or more for the selectionthreshold of the white line lap ratio.

(2) A protrusion parameter as shown in FIG. 10, which indicates how mucha forward vehicle M2, which is straddling the shoulder line SL and isstationary on the shoulder of the road, protrudes onto the plannedtravel trajectory of the host vehicle M0. The protrusion parameter is aparameter in which a determination element, which relates to whether acollision with the forward vehicle M2 inside the d lane can be avoided,is added to the overlap parameter using road marking information, suchas a white line/yellow line CL serving as a center line, and a shoulderline SL, which represents the detection signal from the camera ECU 22.The selection threshold of the protrusion parameter uses, in addition tothe overlap amount D2 selection threshold, a clearance amount D3selection threshold, which is obtained using the position coordinates ofthe white line CL and the position coordinates of the end portion of theforward vehicle M2 on the host vehicle M0 side, and then calculates thedifference as the separation amount. The clearance amount D3 selectionthreshold uses, for example, a value which is larger than the vehiclewidth of the host vehicle M0 that would enable the host vehicle M0 toproceed as is, but avoid the forward vehicle M2 without crossing thecenter line CL. That is, if there is no possibility of a collisionbetween the forward vehicle M2, which is a stationary vehicle, and thehost vehicle M0 without the host vehicle M0 crossing the center line CL,the forward vehicle M2 is not set as the target vehicle.

When the CPU 101 sets the selection threshold, the process proceeds tostep S164. The CPU 101 calculates the relative lateral distance D1between the forward vehicle M2 and the host vehicle M0, and uses thestationary vehicle threshold Dr2 that has been set to determine whetherthe first determination parameter D1 is less than the selectionthreshold Dr2, and whether the additional parameters D2 and D3 are lessthan the selection threshold (step S164). If at least one of the firstdetermination parameter D1 and the additional parameters D2 and D3 areless than the selection threshold, the CPU 101 proceeds to step S166(step S164: Yes). If at least one of the first determination parameterD1 and the additional parameters D2 and D3 are less than the selectionthreshold, there is a possibility of contact or a collision with thestationary vehicle M2, and it is desirable for it to be set as thetarget vehicle of driving assistance control. If the first determinationparameter D1 and the additional parameters D2 and D3 are all greaterthan or equal to the selection threshold (step S164: No), the CPU 101executes step S170 and ends the present processing routine.

In step S166, the CPU 101 determines whether the setting of thestationary vehicle M2 as a target vehicle should be inhibited based onthe behavior of the host vehicle M0. Inhibiting the setting refers toinhibiting the setting of a target vehicle even when it is determinedthat the target vehicle should be set based on the determinationparameters in step S164, and consequently not setting the targetvehicle. Hereinafter, specific examples will be described.

(3) As shown in FIG. 11, if the host vehicle M0 may perform a coursechange to separate from the stationary vehicle M2, or is executing acourse change, the CPU 101 determines that the stationary vehicle M2 isnot to be set as the target vehicle or included as a candidate for thetarget vehicle (step S166: No), executes step S170, and ends the presentprocessing routine. Using the white line CL detection signal from thecamera ECU 22, it is possible to add as a determination condition a casewhere the host vehicle M0 could change course, or is currently changingcourse, so as to cross the white line CL, that is, a boundary line ofthe current lane, in a direction that causes separation from thestationary vehicle M2. In this case, it is assumed that the host vehicleM0, that is, the driver, is executing an avoidance operation to avoidthe stationary vehicle M2, and therefore, if the stationary vehicle M2is set as the target vehicle, unnecessary driving assistance control isexecuted, which may cause the smooth driving of the host vehicle M0 tobecome hindered as a result of rejection of the avoidance operation bythe driver, thereby resulting in discomfort to the driver. Therefore,the occurrence of these problems can be prevented by not setting thestationary vehicle M2 as the target vehicle in a case where the hostvehicle M0 may change course, or is currently changing course, toseparate from the stationary vehicle M2.

(4) As shown in FIG. 12, if the host vehicle M0 may change course, or iscurrently changing course, so as to approach the stationary vehicle M2,the CPU 101 determines the stationary vehicle M2 is to be set as thetarget vehicle or is included as a candidate for the target vehicle(step S166: Yes), then executes step S140, and ends the presentprocessing routine. Using the white line CL detection signal from thecamera ECU 22, it is possible to add as determination conditions a casewhere the host vehicle M0 has crossed the white line CL that divides thecurrent lane, that is, the host vehicle M0 is currently traveling in thesame lane as the stationary vehicle M2, and a case where, as shown inFIG. 13, the stationary vehicle M2, which has stopped on the shoulder ofthe road, is straddling the same shoulder line SL as the host vehicleM0. In this case, the host vehicle M0, that is, the driver, hasapproached the stationary vehicle M2, and the execution of drivingassistance control is desired. Therefore, if a course change that maycause the host vehicle M0 to approach the stationary vehicle M2 may beperformed, or if a course change is being performed, the stationaryvehicle M2 is set as the target vehicle such that contact or a collisionbetween the stationary vehicle M2 and the host vehicle M0 is inhibitedor avoided. If a course change that may cause the host vehicle M0 toapproach the stationary vehicle M2 may be performed, or if a coursechange is being performed, the stationary vehicle M2 is excluded frombeing set as the target vehicle when three or more travel lanes exist,the stationary vehicle M2 is present in the lane closest to the shoulderof the road, and the host vehicle M0 is performing a course change fromthe center lane to the lane which is second closest to the shoulder ofthe road. This is because, in this case, the host vehicle M0 has notplanned to perform a course change to the rear of the stationary vehicleM2, and setting the stationary vehicle M2 as the target vehicle wouldcause driving assistance control to be executed, thereby hindering thesmooth travel of the host vehicle M0.

The possibility of a course change that causes the host vehicle M0 toapproach or separate from the stationary vehicle M2, or the execution ofa course change, may be determined, for example, from the orientation ofthe host vehicle M0 using the detection signal from the yaw rate sensor23, and the steering angle of the host vehicle M0 using the detectionsignal from the rotation angle sensor 25. In addition, if the driveroperates the direction indicator, it is possible to determine that acourse change may be performed by using an input signal from thedirection indicator.

If driving assistance control is being executed in the host vehicle M0with respect to a preceding vehicle which is currently moving, the CPU101 may determine whether to inhibit the setting of forward object otherthan the preceding vehicle as the target vehicle. Specific examples willbe described.

(5) As shown in FIG. 14, a forward object ST passed by the precedingvehicle M2, for which driving assistance control is currently beingexecuted, is not to be set as the target vehicle or included as acandidate for the target vehicle (step S166: No), step S170 is executed,and the present processing routine ends. The forward object ST isassumed to be a manhole, and because the preceding vehicle M2 and themanhole ST are in close proximity when the preceding vehicle M2 passesby the manhole ST, the manhole ST may sometimes be determined to be avehicle at the time of execution of fusion processing, and becomeassociated with a flag indicating that an FSN history exists. In thiscase, if the manhole ST is set as the target vehicle, the host vehicleM0 executes inappropriate driving support such as braking, which hindersthe smooth travel of the host vehicle M0. On the other hand, if thepreceding vehicle M2 passed by the forward object, then the host vehicleM0 should also be capable of passing by it without causing a collision,and therefore, the manhole ST is inhibited from being set as the targetvehicle.

(6) As shown in FIG. 15, when a forward object M1 associated with a flagindicating that an FSN history exists, which is detected at the time acourse change is performed by a preceding vehicle M2 for which drivingassistance control is currently being executed, is set as the targetvehicle, or is included as a candidate for the target vehicle (stepS166: Yes), step S140 is executed, and the present processing routineends. That is, setting of the target vehicle is not inhibited. In thiscase, the forward object M1 is determined to be a stationary vehicle,and the forward object M1 is set as the target vehicle in order for acollision or contact between the forward object M1, which is astationary vehicle, and the host vehicle M0 to be avoided or inhibited.

(7) In addition, if the lateral direction distance between a precedingvehicle M2, for which driving assistance control is currently beingexecuted, and the host vehicle M0 is greater than or equal to a firstreference value, it is determined that setting of the target vehicle isnot to be inhibited (step S166: Yes), step S140 is executed, and thepresent processing routine ends. In this case, because the host vehicleM0 is not considered to be traveling on the same travel trajectory asthe preceding vehicle M2, there is a possibility that, similarly to thepreceding vehicle M2, the side of the forward object, which represents astationary vehicle, which is closer to the host vehicle M0 than thepreceding vehicle M2, cannot be passed. Therefore, the forward object isset as the target vehicle in order for a collision or contact betweenthe forward object and the host vehicle M0 to be avoided or inhibited.The lateral direction distance is in the vehicle width direction of thehost vehicle M0, or a direction that intersects with, or is orthogonalto, the direction of travel.

According to the target vehicle setting processing of the secondembodiment, in addition to the advantages obtained from the targetvehicle setting processing of the first embodiment, if a forward objectis associated with a flag indicating that a movement history exists,that is, has been determined as a stationary vehicle, it is possible todetermine whether to perform the setting as the target vehicle in moredetail by using additional parameters. Therefore, if the forward objectis a stationary vehicle, it can more appropriately be set as the targetvehicle, and as a result, an appropriate driving assistance control canbe executed with respect to a stationary vehicle that does not hinderthe smooth travel of the host vehicle.

According to the target vehicle setting processing of the secondembodiment, it is possible to further determine whether to inhibit thesetting of a stationary vehicle as the target vehicle according to thebehavior of the host vehicle. Therefore, a stationary vehicle can bemore appropriately set as the target vehicle by taking the behavior ofthe host vehicle into consideration. As a result, it is possible toinhibit or prevent the execution of driving assistance control thatresults in discomfort to the driver, such as the execution of drivingassistance control when the host vehicle is displaying behavior to avoida stationary vehicle, or driving assistance control not being executedwhen the host vehicle is displaying behavior that brings it into closeproximity to a stationary vehicle.

Further, according to the target vehicle setting processing of thesecond embodiment, during execution of driving assistance control withrespect to a preceding vehicle, which is the target vehicle, it ispossible to further determine whether the setting of the forward objectas a target vehicle is to be inhibited according to the relationshipbetween the preceding vehicle and a forward object associated with aflag indicating that an FSN history exists. Therefore, the targetvehicle can be smoothly switched according to the relationship betweenthe preceding vehicle and the forward object. As a result, for example,it is possible to inhibit or prevent the execution of driving assistancecontrol accompanied by braking or acceleration that results indiscomfort to the driver.

In the second embodiment, the setting of the target vehicle may beinhibited by reducing the degree to which vehicles are set as the targetvehicle. For example, by associating one or more coefficients with thebehavior of the host vehicle with respect to the target vehicle, and notsetting the target vehicle when the coefficient is greater than adetermination threshold, the degree to which a forward object, which hasbeen determined to be set as the target vehicle based on the stationaryvehicle parameter, is set to the target vehicle is reduced. Inparticular, if a plurality of candidates for the target vehicle areselected based on the stationary vehicle parameter, by using acoefficient that takes into consideration the behavior of the hostvehicle described above and the relationship between the host vehicleand the forward object, and a single forward object having the largestor smallest coefficient value is set as the target vehicle, the degreeto which the other forward object are set as the target vehicle isreduced.

Third Embodiment

Next, driving assistance control processing according to a thirdembodiment will be described with reference to FIG. 16. The drivingassistance control processing is a detailed specific example of thedriving assistance control processing in step S20 shown in FIG. 3, whichexecutes constant travel speed/inter-vehicle distance control processing(ACC). The CPU 101 acquires information about a forward object (stepS200). The information about the forward object is so-called attributeinformation acquired via the radar ECU 21 and the camera ECU 22. The CPU101 uses the acquired information to determine whether the forwardobject is the target vehicle (step S210). The target vehicle is alsoreferred to as a preceding vehicle. Whether the forward object is thetarget vehicle can be determined by a flag associated with the forwardobject when the target vehicle is set in the target vehicle settingprocessing described above.

If it is determined that the forward object is the target vehicle (stepS210: Yes), the CPU 101 executes constant travel speed/inter-vehicledistance control processing (step S220), and ends the present processingroutine. The constant travel speed/inter-vehicle distance controlprocessing is realized as a result of the CPU 101, which executes thedriving assistance control program P2, transmitting a throttle openinglevel instruction signal to the throttle drive device 31 such that a setspeed is maintained, and further, transmitting a throttle opening levelinstruction signal to the throttle drive device 31 to maintain a presetinter-vehicle distance, and a braking instruction signal to the brakeassistance device 32 to realize a required deceleration rate.

If it is determined that the forward object is not the target vehicle(step S210: No), the CPU 101 ends the present processing routine.

According to the driving assistance control processing of the thirdembodiment, because constant travel speed/inter-vehicle distance controlprocessing is executed with respect to a forward object set as thetarget vehicle by the first and second embodiments, excessive brakingand acceleration is inhibited, and collisions or contact between theforward object and the host vehicle can also be reduced or prevented.The execution of the constant travel speed/inter-vehicle distancecontrol processing may be interrupted under conditions where the forwardobject cannot be decelerated and stopped by the constant travelspeed/inter-vehicle distance control processing. In this case, emergencybraking (EBA) may be executed as the driving assistance control. In thethird embodiment, when braking assistance or steering assistance isexecuted as the driving assistance control processing, becausedeceleration, acceleration and steering support are executed withrespect to a forward object which has been appropriately set, excessiveexecution of driving assistance control is inhibited, while alsoenabling collisions or contact between the forward object and the hostvehicle to be reduced or prevented.

Other Embodiments

(1) In the second embodiment, a forward object associated with a flagindicating that an FSN history exists may also be set as the targetvehicle by further adding an arbitrary combination of additionalconditions, including the speed of the host vehicle M0 being less thanor equal to a specified value, a collision spare time TTC with a forwardobject associated with a flag indicating that an FSN history existsbeing less than or equal to a specified value, the distance from aforward object associated with a flag indicating that an FSN historyexists being less than or equal to a specified value, and whetherdeceleration and stopping can be achieved by the driving assistancecontrol. These conditions are conditions which enable collisions orcontact with a forward object set as the target vehicle to be avoided orinhibited by executing the driving assistance control, or conditionsthat are expected to enable collisions or contact with a forward objectset as a target vehicle to be avoided or inhibited by executing thedriving assistance control. Therefore, by taking these conditions intoconsideration, it is possible to determine whether to set the forwardobject as the target vehicle from the perspective of the effectivenessof the driving assistance control.

(2) In the second embodiment, the order in which steps S164 and S166 areexecuted may be reversed. For example, if it is a priority determinationcondition to inhibit the setting of the target vehicle, step S166 may beexecuted first.

(3) In the embodiments described above, the CPU 101 executes the programfor setting a target vehicle P1 and the program for driving assistanceP2 to realize the setting control unit and driving assistance control bysoftware, but these may also be realized by hardware by means of apre-programmed integrated circuit or discrete circuit.

The present disclosure has been described above based on embodiments andmodifications, however the embodiments of the invention described aboveare intended to facilitate an understanding of the present disclosure,and in no way limit the present disclosure. The present disclosure maybe modified and improved without departing from the spirit and scope ofthe claims, and equivalents thereof are also included in the presentdisclosure. For example, the technical features in the embodiments andmodifications that correspond to the technical features in each of themodes described in the Summary of the Invention section may beappropriately replaced or combined to solve some or all of the problemsdescribed above, or to achieve some or all of the effects describedabove. Furthermore, if the technical feature is not described asessential within the present specification, it can be eliminated asappropriate. For example, Application Example 1 represents the devicefor setting a target vehicle in a vehicle according to the first aspectdescribed above.

Application Example 2: The device for setting a target vehicle accordingto Application Example 1, wherein the first determination parameter is arelative lateral direction distance between the target vehicle and ahost vehicle.

Application Example 3: The device for setting a target vehicle accordingto Application Example 1 or 2, wherein the setting control unit alsouses an additional parameter in addition to the first determinationparameter to determine whether to set the forward object as the targetvehicle if a combination history is associated with the forward object.

Application Example 4: The device for setting a target vehicle accordingto Application Example 3, wherein the additional parameter includes atleast one of a vehicle width direction overlap amount between theforward object and the host vehicle, and a vehicle width directionclearance amount between the forward object and a road marking thatdefines a travel lane of the host vehicle.

Application Example 5: The device for setting target vehicle accordingto any one of Application Examples 1 to 4; wherein the setting controlunit inhibits the setting of the forward object as the target vehicle ifthe driving assistance control is being executed with respect to thetarget vehicle.

Application Example 6: The device for setting a target vehicle accordingto Application Example 5, wherein the setting control unit does notinhibit the setting of the forward object as the target vehicle if arelative lateral direction distance between the target vehicle and thehost vehicle is greater than or equal to a first reference value.

Application Example 7: The device for setting a target vehicle accordingto Application Example 5, wherein the setting control unit does notinhibit the setting of the forward object as the target vehicle if thetarget vehicle has performed a course change.

Application Example 8: The device for setting target vehicle accordingto any one of Application Examples 1 to 4; wherein the setting controlunit inhibits the setting of the forward object as the target vehicle ifa course change may be performed that results in the host vehicleseparating from the forward object, or if a course change is beingexecuted.

Application Example 9: The device for setting target vehicle accordingto any one of Application Examples 1 to 4; wherein the setting controlunit does not inhibit the setting of the forward object as the targetvehicle if a course change may be performed that results in the hostvehicle approaching the forward object, or if a course change is beingexecuted.

Application Example 10: A system for setting a target vehicle,including: a device for setting target vehicle according to any one ofApplication Examples 1 to 9; a first detection unit that outputs thefirst detection signal; and a second detection unit that outputs thesecond detection signal.

Application Example 11: The system for setting a target vehicleaccording to Application Example 10, wherein a constant travelspeed/inter-vehicle distance control unit that executes constant travelspeed/inter-vehicle distance control processing with respect to thetarget vehicle that has been set.

What is claimed is:
 1. A driving support device that performs travelingto follow a preceding vehicle traveling in front of a host vehicle, thedriving support device comprising: a first detection unit that detectsan object in front of the host vehicle at a reflection point, a seconddetection unit that detects the object using an image, and a controlunit that is communicably connected to the first detection unit and thesecond detection unit, wherein the control unit selects the object,which is a moving object detected by the first detection unit or thesecond detection unit, or a stationary object detected by the firstdetection unit or the second detection unit, determined to be a vehicleby the first detection unit and the second detection unit as a target oftraveling to follow.
 2. The driving support device according to claim 1,wherein the control unit further selects the moving object detected bythe first detection unit or the second detection unit as a target oftraveling to follow regardless of whether the moving object is a vehicledetermined by the first detection unit and the second detection unit. 3.The driving support device according to claim 1, wherein the controlunit further selects the moving object detected by the first detectionunit or the second detection unit as a target of traveling to followwith priority over the stationary object detected by the first detectionunit or the second detection unit and determined to be a vehicle by thefirst detection unit and the second detection unit.
 4. The drivingsupport device according to claim 1, wherein the control unit does notselect the moving object as a target of traveling to follow when therelative lateral distance between the object and the host vehicle isequal to or greater than a predetermined value.
 5. The driving supportdevice according to claim 1, wherein the control unit does not selectthe moving object as a target of traveling to follow when the amount ofoverlap between the object and the host vehicle in the lateral directionis less than a predetermined value
 6. A driving support method thatperforms traveling to follow a preceding vehicle traveling in front of ahost vehicle, the driving support method comprising: detecting an objectin front of the host vehicle at a reflection point by a first detectionunit, detecting the object using an image by a second detection unit,and selecting a moving object detected by the first detection unit orthe second detection unit, or a stationary object detected by the firstdetection unit or the second detection unit, which is an objectdetermined to be a vehicle by the first detection unit and the seconddetection unit, as traveling to follow by a control unit communicablyconnected to the first detection unit and the second detection unit. 7.A driving support program that performs traveling to follow a precedingvehicle traveling in front of a host vehicle, the driving supportprogram stored in a nonvolatile, non-transitory computer readable mediumwhich causes a computer to execute the processing of: detecting anobject in front of the host vehicle at a reflection point by a firstdetection unit, detecting the object using an image by a seconddetection unit, and selecting a moving object detected by the firstdetection unit or the second detection unit, or a stationary objectdetected by the first detection unit or the second detection unit, whichis an object determined to be a vehicle by the first detection unit andthe second detection unit, as traveling to follow by a control unitcommunicably connected to the first detection unit and the seconddetection unit.